Kitchen Aid Mixer

I have a wonderful kitchen aid stand mixer,i have used it a few times,but my question is,when mixing the mixture for cakes how long to mix,i have done 4mins on no4 speed,is this long enough?,this is just butter and sugar then i do all the other ingredients the same time eggs and flour.The last few cakes have been a flop not as good as hand mixing,is it the speed or not long enough mixing??.My mixer is brill i think its the operater .

I've got a kenwood mixer & either do an all in one mix or cream the fat & sugar until light & fluffy & no crunchy sugar can be felt on the bottom of the bowl, then add beaten eggs a bit at a time with a little flour to stop it curdling, then fold in the flour. Sounds like you aren't getting any air in or knocking the air out by adding eggs & flour together

Thanks for the reply i will do as you suggest and just do the eggs a bit at a time,i want to get this right as i like to bake i don't want to be put off by a few miss haps,these mixers are expensive so i want to get the most out of it.Lillileaf